#pragma once
/**
 * @file brep_face_split.h
 * @brief B-Rep face splitting by plane
 *
 * Splits faces that partially intersect a cutting plane, producing
 * cleanly separated face fragments. Used to improve boolean operation
 * quality by replacing coarse centroid-based IN/OUT classification
 * with precise geometric splitting.
 *
 * @ingroup brep
 */
#include "vde/brep/brep.h"
#include "vde/core/point.h"
#include <vector>

namespace vde::brep {

/**
 * @brief Split a face by a plane
 *
 * Cuts a single B-Rep face with an infinite plane, producing up to
 * two face fragments (one on each side of the plane). Each fragment
 * is a valid BrepModel with proper loop topology.
 *
 * **Algorithm:**
 * 1. Get the face's ordered vertices by traversing the outer loop
 * 2. Classify each vertex as positive (distance ≥ 0) or negative (distance < 0)
 * 3. If all vertices are on the same side: return the face as a single fragment
 * 4. Otherwise: build two new faces:
 *    - Face A: vertices on the positive side + intersection points
 *    - Face B: vertices on the negative side + intersection points
 *
 * @param body Source B-Rep body containing the face
 * @param face_id Index of the face to split
 * @param plane_point A point on the cutting plane
 * @param plane_normal Normal vector of the cutting plane (need not be unit-length)
 * @return Vector of 0, 1, or 2 face fragment BrepModels
 *
 * @code{.cpp}
 * auto box = make_box(2, 2, 2);
 * // Split face 0 of the box with the YZ plane (x=0)
 * auto frags = split_face_by_plane(box, 0, Point3D(0,0,0), Vector3D(1,0,0));
 * // frags.size() == 2: left half and right half
 * for (auto& f : frags) {
 *     // Each fragment has its own vertices, edges, loop, and surface
 *     assert(f.is_valid());
 * }
 * @endcode
 */
[[nodiscard]] std::vector<BrepModel> split_face_by_plane(
    const BrepModel& body, int face_id,
    const core::Point3D& plane_point,
    const core::Vector3D& plane_normal);

}  // namespace vde::brep